This tachnical note presents on the results of the field test on the motion of the catamaran ship UZUSHIO which belongs to The Third Port and Harbour Construction Bureau.
　By this test, the characteristics of the motion of the ship was investigated changing the speed of the ship. The error of sounding and positioning operation of the ship produced by the ship motion and the fundamental investigation of physical influence upon crew, such as motion sickness, were also examined. The results of the test were as follows.
　The fluctuation of average rolling angles and average pitching angles were both around 1.0 degree and they are nearly constant at all speeds. The ship had a list with the maximum angle of 5.4 degree, caused by pitching rather than caused by rolling.
　The error values of sounding and positioning produced by the ship motion were both within those of surveying machines that the ship loads. It was found by this test that the larger sounding errors were caused mainly by rolling rather than pitching of the ship, while the positioning errors were greatly influenced by pitching.
　For the investigation of physical influence on crew caused by the ship motion, the vibration acceleration and frequency of the ship were measured. But the measured values of them in this test were generally so small that no physical influence on the crew seems to be produced by the ship motion.
　Judging from the results described above, it can be considered that tha ship UZUSHIO has the ability enough to work for survey operations.